JP3592397B2 - Heat bonding method for two kinds of members having different thermal expansion rates - Google Patents

Description

【００２３】
また希土類元素系合金における亜、過共晶合金としては以下のものを挙げることができる。各化学式において、数値の単位は原子％である（これは以下同じ）。
（ａ） Ｎｄ_６０Ｃｕ_４０合金、Ｎｄ_７５Ｃｕ_２５合金、Ｎｄ_８０Ｃｕ_２０合金、Ｎｄ_５０Ｃｕ_５０合金……液相発生温度５２０℃（図４参照）
（ｂ） Ｓｍ_７５Ｃｕ_２５合金、Ｓｍ_６５Ｃｕ_３５合金……液相発生温度５９７℃
（ｃ） Ｎｄ_９０Ａｌ_１０合金（液相発生温度６３４℃）、Ｎｄ_８０Ｃｏ_２０合金（液相発生温度５９９℃）、Ｌａ_８５Ｇａ_１５合金（液相発生温度５５０℃）
さらに三元系合金としては、Ｎｄ_６５Ｆｅ_５ Ｃｕ_３０合金（液相発生温度５０１℃）およびＮｄ_７０Ｃｕ_２５Ａｌ_５ 合金（液相発生温度４７４℃）を挙げることができる。
【００２４】
加熱時間ｈは、それが長過ぎる場合には永久磁石１および積層体３の特性変化を招来するので、ｈ≦１０時間であることが望ましく、生産性向上の観点からはｈ≦１時間である。
〔実施例１〕
先ず、以下に述べる方法で、非晶質相の体積分率ＶｆがＶｆ＝１００％であるろう材用箔材を製造した。
【００２５】
純度９９．９％のＮｄと、純度９９．９％のＣｕと、純度９９．９％のＡｌとを、Ｎｄ_７０Ｃｕ_２６Ａｌ_４ 合金が得られるように秤量し、次いでその秤量物を真空溶解炉を用いて溶解し、その後鋳造を行ってインゴットを得た。
【００２６】
このインゴットから約５０ｇの原料を採取し、これを石英ノズル内で高周波溶解して溶湯を調製し、次いで溶湯を石英ノズルのスリットから、その下方で高速回転するＣｕ製冷却ロール外周面にアルゴンガス圧により噴出させて超急冷し、幅３０ｍｍ、厚さ５０μｍのＮｄ_７０Ｃｕ_２６Ａｌ_４ 合金よりなる薄帯を得た。
【００２７】
この場合の製造条件は次の通りである。石英ノズルの内径：４０ｍｍ；スリットの寸法：幅 ０．２５ｍｍ；長さ ３０ｍｍ；アルゴンガス圧：１．５ｋｇｆ／ｃｍ^２ 、溶湯温度；６７０℃；スリットと冷却ロールとの距離：１．０ｍｍ；冷却ロールの周速：１３ｍ／ｓｅｃ ；溶湯の冷却速度 約１０^５ Ｋ／ｓｅｃ ．
図５は薄帯のＸ線回折結果を示し、この薄帯においては２θ≒３２°に幅広のハローパターンが観察され、このことから薄帯の金属組織は非晶質単相組織であることが判明した。また薄帯は高い靱性を有し、１８０°密着曲げが可能であった。
【００２８】
次に、Ｎｄ_７０Ｃｕ_２６Ａｌ_４ 合金よりなる非晶質薄帯から、縦１００ｍｍ、横２０ｍｍ、厚さ５０μｍの箔材を切出した。
【００２９】
永久磁石１として、縦１００ｍｍ、横２０ｍｍ、厚さ６ｍｍのＮｄＦｅＢ系永久磁石（住友特殊金属社製、商品名ＮＥＯＭＡＸ−２８ＵＨ、キュリー点＝３１０℃）を選定した。また積層体３として、縦４０ｍｍ、横２０ｍｍ、厚さ０．４ｍｍの接合用冷間圧延鋼板２ａと、縦３５ｍｍ、横２０ｍｍ、厚さ０．２ｍｍの凹部用冷間圧延鋼板２ｂとを図１に示すように積層してなり、且つ縦４０ｍｍ、横２０ｍｍ、長さ１００ｍｍの直方体状の積層体を選定した。この場合、小接合面４の面積は２０ｍｍ×０．４ｍｍ＝８ｍｍ^２ 、凹部５の深さは４０ｍｍ−３５ｍｍ＝５ｍｍ、幅は０．２ｍｍ、長さは２０ｍｍである。
【００３０】
図１に示すように、積層体３の接合面７上に、１枚の箔材（厚さ５０μｍ）よりなるろう材１０または２枚以上の箔材を重ね合せてなるろう材１０を、またそのろう材１０の上に永久磁石１をその接合面９を下向きにしてそれぞれ重ね合せ、その重ね合せ物を真空加熱炉内に設置して、加熱温度Ｔ＝５３０℃、加熱時間ｈ＝２０分間の加熱工程、それに次ぐ炉冷よりなる冷却工程を行って、図２に示すように永久磁石１と積層体３とをろう材層９を介し接合した接合体１２の例１〜５を得た。この加熱接合処理においては、加熱温度ＴがＴ＝５３０℃であって液相発生温度４７４℃を超えているので、ろう材１０は液相状態となる。
【００３１】
表２は、接合体１２の例１〜５に関する、ろう材１０の厚さ（箔材の厚さ５０μｍ×使用枚数）、永久磁石１外面への過剰ろう材ａの付着の有無および永久磁石の割れの有無を示す。
【００３２】
【表２】

【００３３】
表２から明らかなように、例１〜５においては、永久磁石１外面への過剰ろう材ａの付着および永久磁石１の割れは生じておらず、永久磁石１と積層体３とがろう材層１１を介して強固に接合されていた。これは、前記のように、凹部５を持つ積層体３を用いたことにより、過剰ろう材の食出しが防止されると共に加熱工程後の冷却工程で接合部に生じる熱応力が緩和されたからである。
【００３４】
比較のため、凹部を持たない積層体として、接合用冷間圧延板２ａと同一寸法、したがって縦４０ｍｍ、横２０ｍｍ、厚さ０．４ｍｍの冷間圧延鋼板を積層してなり、且つ縦４０ｍｍ、横２０ｍｍ、長さ１００ｍｍの直方体状の積層体を用い、前記と同様の方法で５種の接合体を得た。これら接合体において、ろう材の厚さが５０〜５００μｍである場合には異常はなかったが、ろう材の厚さを５５０μｍに設定すると、両接合面間から過剰ろう材が食出して永久磁石外面に玉状になって付着し、その結果、永久磁石に割れが発生した。
【００３５】
また比較のため、積層体３の代りに、炭素鋼（ＪＩＳ Ｓ３５Ｃ）よりなり、且つ積層体３と同一寸法のブロック体を用い、前記と同様の方法で５種の接合体を得た。これらの接合体においては、ろう材の厚さ、即ち、５０〜５５０μｍに関係なく、全ての永久磁石全体に割れが発生し、特に熱応力が集中する各永久磁石の周辺部は割れが大きかった。これは永久磁石とブロック体との熱膨脹率の差が大きいことに起因する。
【００３６】
なお、積層体３もブロック体と略同様の熱膨脹率を有するが、積層構造により前記のような熱応力緩和効果が得られるので、ブロック体を用いた場合の問題は回避される。
〔実施例２〕
実施例１で述べたＮｄ_７０Ｃｕ_２６Ａｌ_４ 合金よりなる非晶質薄帯から、縦１０ｍｍ、横１０ｍｍ、厚さ５０μｍの箔材を切出した。
【００３７】
永久磁石１として、縦１０ｍｍ、横１０ｍｍ、厚さ３ｍｍのＮｄＦｅＢ系永久磁石（住友特殊金属社製、商品名ＮＥＯＭＡＸ−２８ＵＨ、キュリー点＝３１０℃）１を選定した。また積層体３として、縦１５ｍｍ、横１０ｍｍ、厚さ０．３ｍｍの接合用冷間圧延鋼板２ａと、縦１３ｍｍ、横１０ｍｍ、厚さ０．１ｍｍの凹部用冷間圧延鋼板２ｂとを図６に示すように（図１の場合と同様に）積層してなり、且つ縦１０．３ｍｍ、横１０ｍｍ、長さ１５ｍｍの直方体状の積層体を選定した。この場合、小接合面４の面積は１０ｍｍ×０．３ｍｍ＝３ｍｍ^２ 、凹部５の深さは１５ｍｍ−１３ｍｍ＝２ｍｍ、幅は０．１ｍｍ、長さは１０ｍｍである。
【００３８】
そして、１つの積層体３の接合面７上に１枚の箔材（５０μｍ）よりなるろう材１０または２枚以上の箔材を重ね合せてなるろう材１０を、またろう材１０の上に一方の接合面９を下向きにした永久磁石１を、さらに永久磁石１の他方の接合面９上に、前記同様のろう材１０を、さらにまたろう材１０の上にもう１つの積層体３をその接合面７を下向きにしてそれぞれ重ね合せて重ね合せ物を作製した。次いで、重ね合せ物を真空加熱炉内に設置し、加熱温度Ｔ＝５３０℃、加熱時間ｈ＝２０分間の加熱工程、それに次ぐ炉冷よりなる冷却工程を行って、図７に示すように２つの積層体３により永久磁石１を挟むようにそれら１，３をろう材層１１を介し接合した接合体１２の例１〜５を得た。この加熱接合処理においては、前記同様に加熱温度ＴがＴ＝５３０℃であるからろう材１０は液相状態となる。これらの例１〜５においては、永久磁石１外面への過剰ろう材ａの付着および永久磁石１の割れは生じていなかった。なお、両積層体３に存する貫通孔１４は引張り試験においてチャックとの連結に用いられる。
【００３９】
比較のため、凹部を持たない積層体として、接合用冷間圧延鋼板２ａと同一寸法、したがって縦１５ｍｍ、横１０ｍｍ、厚さ０．３ｍｍの冷間圧延鋼板を積層してなり、且つ縦９．９ｍｍ、横１０ｍｍ、長さ１５ｍｍの直方体状の積層体を用い、前記と同様の寸法で接合体の例１ａ〜５ａを得た。これらの例１ａ〜５ａにおいて、厚さが５５０μｍのろう材を用いた例５ａでは、過剰ろう材の永久磁石外面への付着および永久磁石の割れが発生していた。
【００４０】
次いで、例１〜５、１ａ〜５ａについて室温下で引張り試験を行ったところ、表３の結果を得た。
【００４１】
【表３】

【００４２】
表３において、例１〜４および例１ａ〜４ａの引張強さはろう材層の破断による値である。対応する例１と１ａ、例２と２ａ、例３と３ａ、例４と４ａを比較すると、例１ａ〜２ａの方が例１〜４よりも僅かではあるが接合強度が高い。これは例１ａ〜４ａの方が例１〜４よりも積層体接合面の面積が大きいことに起因する。
【００４３】
例５と５ａとを比べると、それらの接合強度には大きな差が生じている。これは、例５が健全であるので、その破断がろう材層１１において発生しているのに対し、例５ａでは永久磁石に割れが生じているので、その破断が永久磁石において発生していることに起因する。なお、例１〜５の接合強度は、高温下、例えば１５０℃の加熱下においても、室温下のそれと略同じである。
【００４４】
前記接合技術は、図８，９に示すように、回転機としてのモータのロータ１５において、その成層鉄心（積層体）３に対する永久磁石１の接合に適用され、回転数が１００００ｒｐｍ 以上である高速回転モータの実現を可能にするものである。
【００４５】
成層鉄心３を構成する複数の鋼板（板材）２は、積層方向に並ぶ外周面（外面）の少なくとも一部を小接合面４とする複数の接合用冷間圧延鋼板（接合用板材）２ａと、隣接する両接合用冷間圧延鋼板２ａ間の全てに挟着されると共に凹部５を形成すべく、積層方向に並ぶ外周面（外面）６の少なくとも一部、図示例では全部を小接合面４よりも引込ませた複数の凹部用冷間圧延鋼板（凹部用板材）２ｂとよりなる。したがって、成層鉄心３の複数の接合面７は複数の接合用冷間圧延鋼板２ａによる小接合面４より形成される。
【００４６】
図中、１６は回転軸であり、その回転軸１６は成層鉄心３にスプライン結合され、その成層鉄心３の一端部が回転軸１６に溶接１７される。この場合、回転軸１６を成層鉄心３にスプラインを介し圧入してもよい。
【００４７】
図１０は成層鉄心３の他例を示す。その成層鉄心３の複数の接合面７は、複数の冷間圧延鋼板（板材）２における積層方向に並ぶ外周面（外面）の少なくとも一部である小接合面４より形成される。接合面７の両側に凹部５が形成され、それら凹部５は各小接合面４に隣接して積層方向に延びている。
【００４８】
この成層鉄心３に前記同様の方法で永久磁石１を接合したところ、過剰ろう材ａの永久磁石１外面への付着および永久磁石１の割れは発生しなかった。
【００４９】
接合条件は次の通りである。成層鉄心：長さ１０４ｍｍ、冷間圧延鋼板の厚さ０．４ｍｍ、小接合面の面積１９ｍｍ×０．４ｍｍ＝７．６ｍｍ^２ 、凹部の深さ３ｍｍ、幅０．５ｍｍ、長さ１０４ｍｍ；永久磁石：縦１０４ｍｍ、横２０ｍｍ、厚さ５ｍｍのＮｄＦｅＢ系永久磁石（住友特殊金属社製、商品名ＮＥＯＭＡＸ−２８ＵＨ、キュリー点＝３１０℃）；ろう材：非晶質Ｎｄ_７０Ｃｕ_２６Ａｌ_４ 合金よりなる、縦１０４ｍｍ、横２０ｍｍ、厚さ５０μｍの箔材を用い、ろう材の厚さを、箔材を重ね合わせることにより１００，２００，５００，５５０μｍの４段階に変化させた；永久磁石に対する押圧手段：永久磁石１個当り、押圧力１．５ｋｇのスプリングを２本使用；加熱温度Ｔ：５３０℃；加熱時間ｈ：４０分間．
なお、永久磁石１には、前記加熱接合処理後において着磁処理が施される。
【００５０】
【発明の効果】
本発明によれば、前記のように特定された手段を用いることによって、熱膨脹率を異にする二種の部材を、加熱工程後の冷却工程での熱膨脹率が小さい方の部材が脆い場合にもその部材における割れ発生を回避して、強固に加熱接合することができる。
【図面の簡単な説明】
【図１】永久磁石、ろう材および積層体の重ね合せ関係の一例を示す斜視図である。
【図２】接合体の一例を示す要部断面図である。
【図３】加熱接合メカニズムを示す説明図である。
【図４】Ｃｕ−Ｎｄ系状態図の要部を示す。
【図５】Ｎｄ_７０Ｃｕ_２６Ａｌ_４ 合金のＸ線回折図である。
【図６】永久磁石、ろう材および積層体の重ね合せ関係の他例を示す斜視図である。
【図７】接合体の他例を示す斜視図である。
【図８】要部を拡大したモータ用ロータの断面図で、その破断位置は図９に８−８線で示す。
【図９】要部を破断した、図８の９−９矢視図である。
【図１０】成層鉄心の要部斜視図である。
【符号の説明】
１ 永久磁石、合金部材（他方の部材）
２ 鋼板（板材）
２ａ 接合用鋼板（接合用板材）
２ｂ 凹部用鋼板（凹部用板材）
３ 積層体、成層鉄心（一方の部材）
４ 小接合面
５ 凹部
６ 端面、外周面（外面）
７，９ 接合面
１０ ろう材
１１ ろう材層
ａ 過剰分[0001]
[Industrial applications]
The present invention relates to a method for heating and joining two members having different coefficients of thermal expansion, in particular, a brazing material is interposed between the joining surfaces of the two members, and the two members are joined using a heating step and a cooling step subsequent thereto. On how to do it.
[0002]
[Prior art]
Conventionally, when a permanent magnet and a steel mounting base are joined, for example, a synthetic resin adhesive has been used (for example, see Japanese Patent Publication No. 61-33939).
[0003]
[Problems to be solved by the invention]
However, joining with a synthetic resin adhesive has problems that the joining strength is remarkably reduced as the temperature of the permanent magnet is increased, and quality control is difficult due to large variation in joining strength.
[0004]
In view of the above, the present invention reduces the thermal stress generated at the joint between the two members while heating and joining the two members by using the brazing material, and at the same time, reduces the excess amount of the brazing material that is edible from between the two joining surfaces. It is an object of the present invention to provide the above-mentioned heat bonding method, which can prevent a member having a smaller coefficient of thermal expansion in a cooling step from being cracked even if the member is brittle in the cooling step by preventing the member from adhering to the outer surface of the member. I do.
[0005]
[Means for Solving the Problems]
In the present invention, a brazing material is interposed between the joining surfaces of two members having different coefficients of thermal expansion, and a heating process and a cooling process subsequent thereto are used to join both members. The joining surface of the one member having a large coefficient of thermal expansion is formed from a plurality of small joining surfaces, and these small joining surfaces are joined to the joining surface of the other member via a brazing material layer, and to the one member, A concave portion adjacent to the small joining surface is formed, and the excess amount of the brazing material is received in the concave portion in the heating step.
[0006]
[Action]
In the above-mentioned heat joining method, the amount of the brazing material to be used is estimated to be larger than the necessary minimum amount in order to form a brazing material layer having a uniform thickness over the entire joint surface. In the heating step, both members expand, for example, their length becomes longer than before heating. On the other hand, the brazing material is in a liquid phase state or a solid-liquid coexisting state, but the excess amount of the brazing material, that is, the excess brazing material is received in the concave portion, so that the excess brazing material edible from between the two joining surfaces is exposed to the outer surface of the member. Is prevented.
[0007]
In the cooling step, in one member having a large coefficient of thermal expansion, each small joint surface forming portion contracts, and the small joint surface is joined to the joint surface of the other member via the brazing material layer. The spacing between the surfaces is greater than before heating, so that one member is constrained to a longer length than before heating. Thus, the thermal stress generated at the joint between the two members is reduced as compared with the case where the length of one member is substantially restored to the length before heating.
[0008]
If the excess brazing material escaping from between the two joining surfaces adheres to the outer surface of the other member in a ball shape, if the other member is brittle, the other member is cracked starting from the attachment portion of the excess brazing material. However, this problem is solved by the recess.
[0009]
In this way, even if the other member having a small coefficient of thermal expansion is brittle, the two members can be firmly joined without causing cracks in the member.
[0010]
【Example】
When two kinds of members having different thermal expansion rates are joined by using a brazing material through a heating step and a subsequent cooling step, as shown in FIG. 1, a member having a smaller thermal expansion rate in the cooling step is used. Was selected as a permanent magnet (alloy member) 1 containing a rare earth element, and a laminate 3 composed of a plurality of steel plates (plate materials) 2 was selected as a member having a larger coefficient of thermal expansion in a cooling step.
[0011]
The steel plate 2 constituting the laminate 3 is adjacent to a plurality of bonding steel plates (bonding plate materials) 2a having at least a part of one end surface (outer surface) arranged in the laminating direction, all of which are small bonding surfaces 4 in the illustrated example. At least a part of one end face (outer face) 6 arranged in the laminating direction, and in the illustrated example, all of the one end face (outer face) 6 sandwiched between all the two joining steel plates 2a and forming the concave portion 5 between the two adjacent small joining faces 4. It is composed of a plurality of recessed steel plates (recessed plate materials) 2b that are drawn in from the small joint surface 4. In this case, the other end surfaces of both steel plates 2a and 2b are on the same plane. Therefore, the joint surface 7 of the laminate 3 is formed from the small joint surfaces 4 made of the plurality of joining steel plates 2a. In the laminate 3, a caulking means 8 or a tightening means using bolts and nuts is used for joining the plurality of joining steel sheets 2a and the recessed steel sheets 2b.
[0012]
Between the joining surfaces 9 and 7 of the permanent magnet 1 and the laminated body 3, a foil-like brazing material 10 that generates a liquid phase at a temperature lower than the melting point thereof or a thin plate-like brazing material 10 in which foil materials are stacked is interposed. In this case, in order to form a brazing material layer having a uniform thickness over the entire joint surfaces 7 and 9, the amount of the brazing material to be used is estimated to be larger than the required minimum amount.
[0013]
In the heat joining, a step of installing a superimposed product composed of the permanent magnet 1, the brazing material 10 and the laminate 3 in a vacuum heating furnace, and the step of bringing the brazing material 10 into a liquid state or a solid-liquid coexisting state under heating. 2 and a cooling step of furnace-cooling the superposed material and joining the permanent magnet 1 and the laminate 3 via the brazing material layer 11 to obtain a joined body 12 as shown in FIG. .
[0014]
FIG. 3 shows the mechanism of the heat bonding. Before the heating in FIG. 3A, the lengths L ₁ of the permanent magnet 1, the brazing material 10, and the laminate 3 forming the superimposed product 13 are equal. During the heating shown in FIG. 3B, the permanent magnet 1 and the laminate 3 expand, the length thereof becomes longer than before heating, and L ₂ > L ₁ , L ₃ > L ₁ (where L ₃ > L). ₂ ) On the other hand, although the brazing material 10 is in a liquid phase state or a solid-liquid coexisting state, the excess amount of the brazing material 10, that is, the excess brazing material a is received in each concave portion 5, so that the brazing material 10 is eroded from between the joint surfaces 7 and 9. The discharged excess brazing material a is prevented from adhering to the outer surface of the permanent magnet 1.
[0015]
After the cooling shown in FIG. 3 (c), in the cooling step, the respective joining steel plates 2a which are the respective small joining surface forming portions of the laminate 3 having the larger coefficient of thermal expansion contract and the respective small joining surfaces 4 become permanent magnets. 1 is joined through the brazing material layer 11 via the brazing material layer 11, so that the distance b between the adjacent small joining surfaces 4 becomes larger than before heating, and as a result, the permanent magnet 1 side of the laminate 3 is is constrained to a long state than the length _{L 1} before _heating, the L 4> _{L 1 (e.g., L 4 ≒ 1.01 × L 1} ). Thereby, the thermal stress generated at the joint is reduced, for example, as compared with the case where the length of the steel block body during heating is substantially restored to the length before heating after cooling.
[0016]
Further, when the excess brazing material a that has erupted from between the joining surfaces 7 and 9 adheres to the outer surface of the permanent magnet 1, if the permanent magnet 1 is brittle, the permanent magnet 1 is cracked starting from the portion where the excess brazing material a is attached. However, this problem is solved by the recess 5.
[0017]
In this way, even if the permanent magnet 1 having a small coefficient of thermal expansion is brittle, the permanent magnet 1 can be firmly joined to the laminate 3 without causing cracks in the permanent magnet 1.
[0018]
The brazing material 10 must exhibit a bonding force at a heating temperature T that does not degrade the magnetic properties of the permanent magnet 1 containing a rare earth element as described above, that is, at T ≦ 650 ° C. Further, this bonding force is manifested by its diffusivity when the brazing material 10 is in a solid state under heating, and when the brazing material 10 is in a liquid phase state or a solid-liquid coexisting state under heating. It is necessary to express by the wettability.
[0019]
From such a viewpoint, a highly active material made of a rare earth element alloy is used as the brazing material 10. In this rare earth element alloy, it is desirable that the volume fraction Vf of the amorphous phase is 50% ≦ Vf ≦ 100%. The reason is as follows. That is, since the amorphous phase does not have a grain boundary layer serving as a starting point of oxidation, the oxidation resistance is extremely high, and the mixture of oxides is small, and the composition is uniform without segregation. This is because it is effective in improving the strength of the brazing material layer 11.
[0020]
In this case, the rare earth element corresponds to at least one selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Alternatively, it is used in the form of a mixture of Mm (misch metal) and Di (didium). The alloying element AE performs a eutectic reaction with a rare earth element, and the alloying element AE includes Cu, Al, Ga, Co, Fe, Ag, Ni, Au, Mn, Zn, Pd, Sn, Sb, and Pb. , Bi, Ge and In. The content of the alloying element AE is set to 5 atomic% ≦ AE ≦ 50 atomic%. When two or more alloying elements AE are contained, the total content thereof is 5 atomic% ≦ AE ≦ 50 atomic%. However, when the content of the alloying element AE is AE> 50 at%, the activity of the rare earth element alloy as the brazing filler metal 10 is impaired. On the other hand, when the AE is less than 5 at%, the liquid phase is sufficiently formed in the solid-liquid coexistence state. It cannot be secured.
[0021]
Table 1 shows an example of a eutectic alloy in a rare earth element alloy.
[0022]
[Table 1]

[0023]
The following may be mentioned as the hypo- and hypereutectic alloys in the rare earth element alloys. In each chemical formula, the unit of the numerical value is atomic% (the same applies hereinafter).
(A) Nd ₆₀ Cu ₄₀ alloy, Nd ₇₅ Cu ₂₅ alloy, Nd ₈₀ Cu ₂₀ alloy, Nd ₅₀ Cu ₅₀ alloy ... liquid phase generation temperature 520 ° C. (see FIG. 4)
_(B) Sm 75 _{Cu 25 alloy,} Sm 65 _{Cu 35} alloy ...... liquid phase generation temperature 597 ° C.
(C) Nd ₉₀ Al ₁₀ alloy (liquid phase generation temperature 634 ° C.), Nd ₈₀ Co ₂₀ alloy (liquid phase generation temperature 599 ° C.), La ₈₅ Ga ₁₅ alloy (liquid phase generation temperature 550 ° C.)
Further, examples of the ternary alloy include an Nd ₆₅ Fe ₅ Cu ₃₀ alloy (liquid phase generation temperature 501 ° C.) and a Nd ₇₀ Cu ₂₅ Al ₅ alloy (liquid phase generation temperature 474 ° C.).
[0024]
The heating time h is desirably h ≦ 10 hours, because if it is too long, it causes a change in the characteristics of the permanent magnet 1 and the laminate 3. From the viewpoint of improving productivity, h ≦ 1 hour. .
[Example 1]
First, a brazing foil material having an amorphous phase volume fraction Vf of 100% was produced by the method described below.
[0025]
Nd having a purity of 99.9%, Cu having a purity of 99.9%, and Al having a purity of 99.9% are weighed so as to obtain an Nd ₇₀ Cu ₂₆ Al ₄ alloy, and then the weighed material is melted in vacuum. Melting was performed using a furnace, and then casting was performed to obtain an ingot.
[0026]
Approximately 50 g of the raw material was collected from this ingot, and this was melted at a high frequency in a quartz nozzle to prepare a molten metal. Then, the molten metal was passed through the slit of the quartz nozzle, and the argon gas was applied to the outer peripheral surface of a Cu cooling roll rotating at high speed below the slit. It was jetted out by pressure and super-quenched to obtain a ribbon made of Nd ₇₀ Cu ₂₆ Al ₄ alloy having a width of 30 mm and a thickness of 50 μm.
[0027]
The manufacturing conditions in this case are as follows. Inner diameter of quartz nozzle: 40 mm; dimensions of slit: width 0.25 mm; length 30 mm; argon gas pressure: 1.5 kgf / cm ² , molten metal temperature: 670 ° C .; distance between slit and cooling roll: 1.0 mm; Circumferential speed of roll: 13 m / sec; cooling speed of molten metal: about 10 ⁵ K / sec.
FIG. 5 shows the results of X-ray diffraction of the ribbon. In this ribbon, a broad halo pattern was observed at 2θ ≒ 32 °, which indicates that the metal structure of the ribbon was an amorphous single-phase structure. found. Further, the ribbon had high toughness and could be bent 180 ° in close contact.
[0028]
Next, a foil material having a length of 100 mm, a width of 20 mm, and a thickness of 50 μm was cut out of an amorphous ribbon made of an Nd ₇₀ Cu ₂₆ Al ₄ alloy.
[0029]
As the permanent magnet 1, an NdFeB-based permanent magnet having a length of 100 mm, a width of 20 mm, and a thickness of 6 mm (manufactured by Sumitomo Special Metals Co., Ltd., trade name NEOMAX-28UH, Curie point = 310 ° C.) was selected. As the laminate 3, a cold-rolled steel plate 2a for joining having a length of 40 mm, a width of 20 mm and a thickness of 0.4 mm and a cold-rolled steel plate 2b for a recess having a length of 35 mm, a width of 20 mm and a thickness of 0.2 mm are shown in FIG. And a rectangular parallelepiped laminate having a length of 40 mm, a width of 20 mm, and a length of 100 mm was selected. In this case, the area of the small joining surface 4 is 20 mm × 0.4 mm = 8 mm ² , the depth of the recess 5 is 40 mm−35 mm = 5 mm, the width is 0.2 mm, and the length is 20 mm.
[0030]
As shown in FIG. 1, a brazing material 10 made of one foil material (thickness: 50 μm) or a brazing material 10 formed by laminating two or more foil materials on a bonding surface 7 of the laminate 3, The permanent magnet 1 is superimposed on the brazing material 10 with the bonding surface 9 facing downward, and the superimposed material is placed in a vacuum heating furnace, where a heating temperature T = 530 ° C. and a heating time h = 20 minutes. 2 and a cooling step consisting of furnace cooling were performed to obtain Examples 1 to 5 of bonded bodies 12 in which the permanent magnet 1 and the laminate 3 were bonded via the brazing material layer 9 as shown in FIG. . In this heat joining process, since the heating temperature T is T = 530 ° C. and exceeds the liquid phase generation temperature 474 ° C., the brazing material 10 is in the liquid phase state.
[0031]
Table 2 shows the thickness of the brazing material 10 (the thickness of the foil material 50 μm × the number of sheets used), the presence or absence of the excessive brazing material a on the outer surface of the permanent magnet 1, and the number of the permanent magnets in Examples 1 to 5 of the joined body 12. Indicates the presence or absence of cracks.
[0032]
[Table 2]

[0033]
As is clear from Table 2, in Examples 1 to 5, no excessive brazing material a adhered to the outer surface of the permanent magnet 1 and no cracking of the permanent magnet 1 occurred, and the permanent magnet 1 and the laminated body 3 formed a brazing material. It was firmly joined via the layer 11. This is because, as described above, the use of the laminate 3 having the concave portions 5 prevents the exudation of the excessive brazing material and alleviates the thermal stress generated at the joint in the cooling step after the heating step. is there.
[0034]
For comparison, as a laminate having no concave portion, a cold-rolled steel plate having the same dimensions as the cold-rolled plate 2a for joining, that is, 40 mm in length, 20 mm in width, and 0.4 mm in thickness is laminated, and 40 mm in length, Using a rectangular parallelepiped laminate having a width of 20 mm and a length of 100 mm, five types of joined bodies were obtained in the same manner as described above. In these joints, there was no abnormality when the thickness of the brazing material was 50 to 500 μm, but when the thickness of the brazing material was set to 550 μm, the excess brazing material was eroded from between the two joining surfaces, and the permanent magnet The beads adhered to the outer surface in a ball shape, and as a result, cracks occurred in the permanent magnet.
[0035]
For comparison, five kinds of joined bodies were obtained in the same manner as described above using a block body made of carbon steel (JIS S35C) and having the same dimensions as the laminated body 3 instead of the laminated body 3. In these joints, cracks occurred in all the permanent magnets irrespective of the thickness of the brazing material, that is, 50 to 550 μm, and the cracks were particularly large in the peripheral portion of each permanent magnet where thermal stress was concentrated. . This is due to the large difference in the coefficient of thermal expansion between the permanent magnet and the block.
[0036]
The laminate 3 also has substantially the same coefficient of thermal expansion as the block, but since the above-described effect of relaxing the thermal stress is obtained by the laminate structure, the problem of using the block is avoided.
[Example 2]
A foil material having a length of 10 mm, a width of 10 mm, and a thickness of 50 μm was cut out of the amorphous ribbon made of the Nd ₇₀ Cu ₂₆ Al ₄ alloy described in Example 1.
[0037]
As the permanent magnet 1, a NdFeB-based permanent magnet (manufactured by Sumitomo Special Metals Co., Ltd., trade name NEOMAX-28UH, Curie point = 310 ° C.) 1 having a length of 10 mm, a width of 10 mm, and a thickness of 3 mm was selected. As the laminate 3, a cold-rolled steel plate 2a for joining having a length of 15 mm, a width of 10 mm and a thickness of 0.3 mm and a cold-rolled steel plate 2b for a recess having a length of 13 mm, a width of 10 mm and a thickness of 0.1 mm are shown in FIG. (See FIG. 1) and a rectangular parallelepiped laminate having a length of 10.3 mm, a width of 10 mm, and a length of 15 mm was selected. In this case, the area of the small joint surface 4 is 10 mm × 0.3 mm = 3 mm ² , the depth of the concave portion 5 is 15 mm−13 mm = 2 mm, the width is 0.1 mm, and the length is 10 mm.
[0038]
Then, a brazing material 10 made of one foil material (50 μm) or a brazing material 10 formed by laminating two or more foil materials on the bonding surface 7 of one laminated body 3 is placed on the brazing material 10 again. A permanent magnet 1 with one joining surface 9 facing downward, a brazing material 10 similar to the above on the other joining surface 9 of the permanent magnet 1, and another laminated body 3 on the brazing material 10. The superposed articles were produced by superposing each other with the bonding surface 7 facing downward. Next, the superimposed product was placed in a vacuum heating furnace, and a heating step of heating temperature T = 530 ° C. and a heating time h = 20 minutes, followed by a cooling step of furnace cooling, was performed, as shown in FIG. Examples 1 to 5 of joined bodies 12 in which the permanent magnets 1 were sandwiched by three laminated bodies 3 and the first and third bodies were joined via a brazing material layer 11 were obtained. In this heat joining process, the brazing material 10 is in a liquid phase state because the heating temperature T is T = 530 ° C. as described above. In these Examples 1 to 5, the attachment of the excessive brazing material a to the outer surface of the permanent magnet 1 and the cracking of the permanent magnet 1 did not occur. In addition, the through-holes 14 present in both the laminates 3 are used for connection with a chuck in a tensile test.
[0039]
For comparison, a cold rolled steel sheet having the same dimensions as the cold-rolled steel sheet 2a for joining, that is, 15 mm in length, 10 mm in width, and 0.3 mm in thickness, is laminated as a laminate having no concave portion, and the vertical length is 9. Using a rectangular parallelepiped laminate having a size of 9 mm, a width of 10 mm, and a length of 15 mm, Examples 1a to 5a of the joined body were obtained with the same dimensions as above. In these Examples 1a to 5a, in Example 5a using a brazing material having a thickness of 550 μm, the excessive brazing material was attached to the outer surface of the permanent magnet and the permanent magnet was cracked.
[0040]
Next, when a tensile test was performed at room temperature on Examples 1 to 5 and 1a to 5a, the results shown in Table 3 were obtained.
[0041]
[Table 3]

[0042]
In Table 3, the tensile strengths of Examples 1 to 4 and Examples 1a to 4a are values obtained by breaking the brazing material layer. Comparing the corresponding Examples 1 and 1a, Examples 2 and 2a, Examples 3 and 3a, and Examples 4 and 4a, Examples 1a to 2a have higher bonding strengths, albeit slightly, than Examples 1-4. This is because Examples 1a to 4a have a larger area of the laminate bonding surface than Examples 1 to 4.
[0043]
When Examples 5 and 5a are compared, a large difference occurs in their bonding strength. This is because, since Example 5 is sound, the fracture occurs in the brazing material layer 11, whereas in Example 5a, the permanent magnet has a crack, and the fracture occurs in the permanent magnet. Due to that. Note that the bonding strengths of Examples 1 to 5 are substantially the same even at a high temperature, for example, at 150 ° C. under heating at room temperature.
[0044]
As shown in FIGS. 8 and 9, the joining technique is applied to the joining of the permanent magnet 1 to the laminated iron core (laminated body) 3 in the rotor 15 of the motor as a rotating machine, and has a high speed of 10,000 rpm or more. This enables the realization of a rotary motor.
[0045]
The plurality of steel plates (sheet materials) 2 constituting the laminated core 3 include a plurality of joining cold-rolled steel plates (joining plate materials) 2 a having at least a part of an outer peripheral surface (outer surface) arranged in the laminating direction as a small joining surface 4. At least a part of the outer peripheral surface (outer surface) 6 arranged in the laminating direction, in the illustrated example, is entirely a small joint surface so as to be sandwiched between all the adjacent cold-rolled steel sheets 2a for joining and to form the concave portion 5. 4 and a plurality of recessed cold-rolled steel plates (recess plate materials) 2b. Therefore, the plurality of joining surfaces 7 of the laminated core 3 are formed from the small joining surfaces 4 of the plurality of cold-rolled steel plates 2a for joining.
[0046]
In the figure, reference numeral 16 denotes a rotating shaft, which is spline-coupled to the laminated core 3, and one end of the laminated core 3 is welded 17 to the rotating shaft 16. In this case, the rotating shaft 16 may be press-fitted into the laminated core 3 via a spline.
[0047]
FIG. 10 shows another example of the laminated core 3. The plurality of joint surfaces 7 of the laminated iron core 3 are formed from the small joint surfaces 4 which are at least a part of the outer peripheral surface (outer surface) of the plurality of cold-rolled steel plates (sheet materials) 2 arranged in the laminating direction. Concave portions 5 are formed on both sides of the joint surface 7, and the concave portions 5 extend in the stacking direction adjacent to each small joint surface 4.
[0048]
When the permanent magnet 1 was joined to the laminated core 3 in the same manner as described above, no adhesion of the excessive brazing material a to the outer surface of the permanent magnet 1 and no cracking of the permanent magnet 1 occurred.
[0049]
The joining conditions are as follows. Laminated core: length 104 mm, thickness of cold-rolled steel sheet 0.4 mm, area of small joint surface 19 mm × 0.4 mm = 7.6 mm ² , recess depth 3 mm, width 0.5 mm, length 104 mm; permanent Magnet: NdFeB-based permanent magnet having a length of 104 mm, a width of 20 mm and a thickness of 5 mm (manufactured by Sumitomo Special Metals Co., Ltd., trade name NEOMAX-28UH, Curie point = 310 ° C.); brazing material: amorphous Nd ₇₀ Cu ₂₆ Al ₄ alloy The thickness of the brazing material was changed in four steps of 100, 200, 500, and 550 μm by laminating the foil materials, using a foil material having a length of 104 mm, a width of 20 mm, and a thickness of 50 μm. Means: Two springs with a pressing force of 1.5 kg are used per permanent magnet; heating temperature T: 530 ° C .; heating time h: 40 minutes.
The permanent magnet 1 is subjected to a magnetizing process after the heat bonding process.
[0050]
【The invention's effect】
According to the present invention, by using the means specified above, the two members having different thermal expansion rates can be used when the member having the smaller thermal expansion coefficient in the cooling step after the heating step is brittle. Also, it is possible to avoid the occurrence of cracks in the member and to perform strong heat bonding.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a superposition relationship between a permanent magnet, a brazing material, and a laminate.
FIG. 2 is a sectional view of a main part showing an example of a joined body.
FIG. 3 is an explanatory view showing a heat bonding mechanism.
FIG. 4 shows a main part of a Cu—Nd system phase diagram.
FIG. 5 is an X-ray diffraction diagram of a Nd ₇₀ Cu ₂₆ Al ₄ alloy.
FIG. 6 is a perspective view showing another example of the overlapping relationship of the permanent magnet, the brazing material, and the laminate.
FIG. 7 is a perspective view showing another example of the joined body.
FIG. 8 is a cross-sectional view of the motor rotor in which a main part is enlarged, and its broken position is indicated by line 8-8 in FIG.
9 is a sectional view taken along the line 9-9 in FIG. 8, with a main part cut away.
FIG. 10 is a perspective view of a main part of a laminated iron core.
[Explanation of symbols]
1 Permanent magnet, alloy member (the other member)
2 Steel plate (plate material)
2a Steel plate for bonding (plate material for bonding)
2b Steel plate for recess (plate material for recess)
3 Laminated body, laminated iron core (one member)
4 Small joining surface 5 Recess 6 End surface, outer peripheral surface (outer surface)
7, 9 joining surface 10 brazing material 11 brazing material layer a excess

Claims (8)

A brazing material (10) is interposed between the joining surfaces (9, 7) of the two members (1, 3) having different thermal expansion rates, and both members (1) are used by using a heating step and a cooling step subsequent thereto. , 3), the joining surface (7) of the one member (3) having a large coefficient of thermal expansion in the cooling step is formed from a plurality of small joining surfaces (4), and these small joining surfaces (4) are formed. 4) is joined to the joining surface (9) of the other member (1) via the brazing material layer (11), and the one member (3) is provided with a concave portion (4) adjacent to the small joining surface (4). (5) forming the heating step, wherein the excess (a) of the brazing material (10) is received in the recess (5) in the heating step; Joining method. The one member is a laminate (3) composed of a plurality of plate members (2), and the plate members (2) have at least a part of an outer surface arranged in the laminating direction as the small joint surface (4). At least a part of the outer surface (6) arranged in the laminating direction is sandwiched between the joining plate (2a) and the adjacent joining plate (2a) to form the concave portion (5) by the small joining. 2. The method according to claim 1, comprising a plurality of recessed plate members (2b) which are recessed from the surface (4). The one member is a laminate (3) composed of a plurality of plate members (2), and a bonding surface (7) of the laminate (3) is at least an outer surface of the plurality of plate members (2) arranged in the laminating direction. 2. The thermal expansion coefficient according to claim 1, wherein the small expansion surface is formed as a part, and the concave portion extends in the laminating direction adjacent to each of the small bonding surfaces. Heat bonding method for various members. 4. The method as claimed in claim 1, wherein the brazing material is made of a rare earth element alloy. In the brazing material (10), the rare earth element is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. element AE is at least one selected Cu, Al, Ga, Co, Fe, Ag, Ni, Au, Mn, Zn, Pd, Sn, Sb, Pb, Bi, Ge, and in, the alloy element AE 5. The method for heating and joining two members having different coefficients of thermal expansion according to claim 4, wherein the content of is 5 atomic% ≦ AE ≦ 50 atomic%. The plate member (2) in the laminate (3) is a steel plate, and the other member (1) having a small coefficient of thermal expansion in the cooling step is an alloy member containing a rare earth element. Or a method of heating and joining two members having different coefficients of thermal expansion according to 5. The method according to claim 6, wherein the alloy member containing the rare earth element is a permanent magnet (1). The method according to claim 2, 3, 4, 5, 6, or 7, wherein the laminate (3) is a laminated core in a rotor (15) of a rotating machine. .

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